[llvm] [SystemZ] SLP reductions: cost functions of reductions and scalarization (PR #112491)

[Jonas Paulsson via llvm-commits]

JonPsson1 wrote:

Patch updated per review.

> The test itself better to precommit in a separate NFC patch anyway.

@uweigand: should we precommit this test now or do we wait until we are ready to actually commit this patch? I can't remember that we have done this type of pre-committing of tests in the past, but rather we wait for performance results and then simply add a test that reflects the new behavior...

https://github.com/llvm/llvm-project/pull/112491